The spark plugs of an internal combustion engine may be located in a sparkplug well at, or near, the top of a cylinder head. A valve cover may be attached to the cylinder head, and may be configured to house engine components such as cam rods, and an oil separator. The components under the valve cover may be kept well oiled. Elongate passages referred to as a spark plug tubes may used in order to keep the oil in the valve cover from contacting the sparkplugs. Electrical connectivity from the electrical system of the vehicle to each spark plug may be made via a corresponding number of Coils On Plug (COPs) positioned in each spark plug tube, and accessible from a top surface of the valve cover. First, or bottom, ends of respective sparkplug tubes may be press fitted into each sparkplug well. Ring shaped radial lip seals, or tube seals, may be used to seal the junction between the valve cover and a second, or top, end of each sparkplug tube.
The inventors herein have recognized three possible paths by which oil may travel from under the valve cover to one or more sparkplugs. The first is between the cylinder head and sparkplug tube; the second is between the radial lip seal and valve cover; and the third is between the radial lip seal and the spark plug tube.
One attempt to keep oil from contacting the sparkplugs is disclosed in US patent publication US 2008/0276918 to Skinner et al. The disclosed approach attempts to eliminate the use of the sparkplug tubes by providing an ignition apparatus with an oil seal integrated with a spark plug boot and configured to mate directly with the cylinder head. A first sealing arrangement is configured to seal the ignition apparatus to the valve cover. A second sealing arrangement includes a circular recessed ring cavity added to the cylinder head circumscribing the spark plug.
The inventors herein have recognized a number of issues with this approach. For example, the cylinder head is modified by adding the ring cavity to receive the annular sealing rib on the bottom end of the disclosed ignition apparatus to form the second sealing arrangement. In addition the ignition apparatus disclosed includes seams along its length that may create additional vulnerabilities to leakage.
The inventors herein have developed a valve cover for an engine that may include a cover body, and a sparkplug tube formed integrally with the cover body. In this way, possible leakage paths between the cylinder head and sparkplug tube or between the radial lip seal and valve cover may be reduced.
One embodiment may include a sealing arrangement on or adjacent a distal end of the sparkplug tube for sealing with a cylinder head. The sealing arrangement may be, for example, an O-ring groove and an O-ring configured for sealing engagement with an annular surface of the sparkplug well in the cylinder head. In this way, any distortion of the bottom end of the sparkplug tubes due to, for example removal and reinstallation may not provide a leakage path. Also in this way, conventional COPs may be used, and the cylinder head may not need modification.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.